[USRP-users] Gen2 reader

mahran nedal mahran2010sawya at hotmail.com
Fri Dec 5 13:37:52 EST 2014


Hello Marcus,
Thank you for your reply and attention . I let my reader to send the carrier wave continuously, But when i plot the received signal i see that the carrier wave after each cycle dropped ,Really i dont know why is that ?  I change the time that when the carrier should power down  to check what happen but with no change on the received signal. I modified the code for buttner that work on usrp 1.the code very large and complicated to mention it. If you know please any one maybe work on this topic .

Thanks,



> Date: Fri, 5 Dec 2014 11:49:15 +0100
> From: marcus.mueller at ettus.com
> To: mahran2010sawya at hotmail.com; usrp-users at lists.ettus.com
> Subject: Re: [USRP-users] Gen2 reader
> 
> Hello Mahran,
> 
> I must admit that I had trouble understanding the complex problem you're
> describing.
> 
> I'll go ahead and try to insert my questions into your mail, so that I
> can get to a full understanding.
> On 12/04/2014 06:40 PM, mahran nedal wrote:
> > yes between transmissions the carrier wave dropped or in every cycle .
> I assume that is correct by design?
> > My implementation based on EPC Class-1 Generation-2 protocol please see http://www.gs1.org/gsmp/kc/epcglobal/uhfc1g2  V2.2 (page 26,42).
> I assume you're referring to the v2.0 document -- there's only a
> two-page v2.2 "fact sheet".
> I must admit that I can't really justify reading a complex standards
> document on worktime -- however, the timing diagram on page 42 indicates
> that the interrogator must continously send, so that is what your
> application must ensure.
> > The reader or interrogator send the signal which contains a Query ,all the  communication parameters  includes inside the query  like preamble ,etc. the signal encoding by pulse interval encoding and modulated by ASK ,the tag receive the signal and back-scattering again to the reader ,through this time the carrier wave energize the tag for response .
> Yes, I understand.
> > I success to read one tag per cycle ,but until now i cant let the carrier wave continuous all the time .
> Why?
> >  What is happening that when the reader send a query to the tag , the tag response its RN16 ,the reader Acknowledged it ,and the tag send the ID after that the carrier wave dropped 
> why do you let the carrier wave drop? The timing diagram says "continous
> wave", so from what I understand you must ensure that your interrogator
> is always either sending data or a naked carrier.
> 
> From what I understand, you are implementing the interrogator, is that
> correct?
> 
> > and start again with each transmission and this is a problem because  when i ran the anti- collision protocol which mean that i should send the number of slots through the query for many tags and every tag choose one slot and response back to the reader ,so i should see through the query for example 3 tag response before the new cycle start but i cant i see just one ,because the carrier wave dropped every cycle.
> Sorry, this I did not understand.
> > Hope to hear from you as soon as Thanks,
> > Eng.Mahran jazi
> Greetings,
> Marcus
> 
> >
> >
> > Date: Wed, 3 Dec 2014 19:03:12 +0100
> > To: usrp-users at lists.ettus.com
> > Subject: Re: [USRP-users] Gen2 reader
> > From: usrp-users at lists.ettus.com
> >
> >
> >   
> >     
> >   
> >   
> >     Hello Mahran
> >
> >     
> >
> >     this is an interesting application.
> >
> >     
> >
> >     I'd like to understand what's going wrong here:
> >
> >     You say the USRP doesn't continously send a carrier wave. I assume
> >     this is happening between your transmissions?
> >
> >     
> >
> >     The USRP will send any signal you want and will try to be as silent
> >     as possible as long as you are not transmitting. If you want a
> >     continous carrier, you will have to continously send samples
> >     containing the appropriate signal. 
> >
> >     Since the N210 architecture is by principle full-duplex capable, as
> >     are the RFX daughterboards, this should normally not be a problem,
> >     unless crosstalk is problematic (e.g. it saturates your RX
> >     amplifiers/mixers).
> >
> >     
> >
> >     Could you please explain in more detail how you transit your signals
> >     (including the carrier)?
> >
> >     
> >
> >     Best regards,
> >
> >     Marcus
> >
> >     
> >
> >     On 12/03/2014 06:51 PM, mahran nedal
> >       via USRP-users wrote:
> >
> >     
> >     
> >       Hi,
> >
> > Im working to implement gen 2 reader based on new generation of usrp n210 with RFX900 daughter board  to read the commercial tags. I success to read commercial tag . now i investigate to read many tags based on dynamic framed slotted aloaha , the main problem that the usrp cant continuously send the carrier wave through one cycle ,the carrier wave dropped and start again with each cycle so i cant sent many slots in each cycle because this problem . i debugging the software no problem . Is there any limitation on this hardware or daughter borad that cant support full-duplex 
> >  
> > Really i need help .
> >
> >
> > Thanks,
> > Eng. jazi
> >  
> >
> >  		 	   		  
> >
> >       
> >
> >       
> >       
> >
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> >
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> >     
> >
> >   
> >
> >
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